Buggy code:
public class Spinner extends Composite { int hwndText ; int hwndUpDown ; boolean ignoreModify ; int pageIncrement ; int digits ; static final int EditProc ; static final TCHAR EditClass = new TCHAR ( 0 , "EDIT" , true ) ; static final int UpDownProc ; static final TCHAR UpDownClass = new TCHAR ( 0 , OS . UPDOWN_CLASS , true ) ; public Spinner ( Composite parent , int style ) { } int callWindowProc ( int hwnd , int msg , int wParam , int lParam ) { } static int checkStyle ( int style ) { } boolean checkHandle ( int hwnd ) { } protected void checkSubclass ( ) { } void createHandle ( ) { } public void addModifyListener ( ModifyListener listener ) { } public void addSelectionListener ( SelectionListener listener ) { } void addVerifyListener ( VerifyListener listener ) { } int borderHandle ( ) { } public Point computeSize ( int wHint , int hHint , boolean changed ) { } public Rectangle computeTrim ( int x , int y , int width , int height ) { } public void copy ( ) { } public void cut ( ) { } int defaultBackground ( ) { } void enableWidget ( boolean enabled ) { } void deregister ( ) { } boolean hasFocus ( ) { } public int getDigits ( ) { } String getDecimalSeparator ( ) { } public int getIncrement ( ) { } public int getMaximum ( ) { } public int getMinimum ( ) { } public int getPageIncrement ( ) { } public int getSelection ( ) { } int getSelectionText ( ) { } int mbcsToWcsPos ( int mbcsPos ) { } public void paste ( ) { } void register ( ) { } void releaseHandle ( ) { } public void removeModifyListener ( ModifyListener listener ) { } public void removeSelectionListener ( SelectionListener listener ) { } void removeVerifyListener ( VerifyListener listener ) { } boolean sendKeyEvent ( int type , int msg , int wParam , int lParam , Event event ) { } void setBackgroundPixel ( int pixel ) { } public void setDigits ( int value ) { } void setForegroundPixel ( int pixel ) { } public void setIncrement ( int value ) { } public void setMaximum ( int value ) { } public void setMinimum ( int value ) { } public void setPageIncrement ( int value ) { } public void setSelection ( int value ) { } void setSelection ( int value , boolean notify ) { } void setToolTipText ( Shell shell , String string ) { } void subclass ( ) { } void unsubclass ( ) { } String verifyText ( String string , int start , int end , Event keyEvent ) { } int widgetExtStyle ( ) { } int windowProc ( int hwnd , int msg , int wParam , int lParam ) { } LRESULT WM_ERASEBKGND ( int wParam , int lParam ) { <START_BUG> LRESULT result = super . WM_ERASEBKGND ( wParam , lParam ) ; <END_BUG> drawBackground ( wParam ) ; return LRESULT . ONE ; } LRESULT WM_KILLFOCUS ( int wParam , int lParam ) { } LRESULT WM_SETFOCUS ( int wParam , int lParam ) { } LRESULT WM_SETFONT ( int wParam , int lParam ) { } LRESULT WM_SIZE ( int wParam , int lParam ) { } LRESULT wmChar ( int hwnd , int wParam , int lParam ) { } LRESULT wmClipboard ( int hwndText , int msg , int wParam , int lParam ) { } LRESULT wmCommandChild ( int wParam , int lParam ) { } LRESULT wmKeyDown ( int hwnd , int wParam , int lParam ) { } LRESULT wmKillFocus ( int hwnd , int wParam , int lParam ) { } LRESULT wmLButtonDown ( int hwnd , int wParam , int lParam ) { } LRESULT wmNotifyChild ( int wParam , int lParam ) { } LRESULT wmScrollChild ( int wParam , int lParam ) { } }

Fix:
super . WM_ERASEBKGND ( wParam , lParam ) ;